At present, a typical wet etching process is as shown in FIG. 1. First, a wafer with a polymer film (e.g., a gallium arsenide wafer) is loaded and placed in a special carrier, and then a manipulator is used to transport the carrier to a process chamber to perform a wet etching process. After the process is completed, the carrier is transported to an unloading position to unload an etched film and wafer. Then, a separation mechanism is used to separate the film and the wafer. Finally, the film and the wafer are unloaded into respective cassettes.
In the above film-from-wafer separation process, an epitaxial lift-off system is generally used. The epitaxial lift-off system is intended to separate a film (e.g., a thin photovoltaic film) from a growing wafer (e.g., a gallium arsenide substrate). The system takes a polymer film fitted to the wafer as an input, and outputs a separate wafer (e.g., a gallium arsenide wafer) and a film adhered to a polymer frame (e.g., a photovoltaic film). The separated film is used for preparing a film solar cell, and the separated wafer or substrate (e.g., a gallium arsenide wafer) can be reused for many times after polishing and cleaning, thereby significantly reducing the cost of thin-film power generation.
Epitaxial lift-off equipment in a gallium arsenide solar cell production line is taken as an example. The bottleneck of the entire equipment is how to complete the separation of a film and a substrate quickly and reliably. In order to obtain a large productivity, in general, there are mainly the following methods:
(1) Two or more sets of manipulators are used. Each of the manipulators separates a film at a time. This method obviously determines to occupy a large space, especially the size of a carrier for transferring the film and the substrate is highly required, and in addition, the coordination between multiple manipulators is also more complicated.
(2) The unloading and separating of multiple films at a time will generally be powered by one separation driving device to simultaneously separate multiple films. For this method, one disadvantage is that when one or several films are separated unsuccessfully during the separation process, the flexibility and fault tolerance of the entire system are not high. Specifically, if the process requires two or three times to retry when the first separation fails, repeated contact will be made for the separated film and substrate. According to the process for manufacturing a gallium arsenide film, such situations are to be avoided as much as possible.
Therefore, it is necessary to design an automated film separation mechanism that can achieve both large productivity and independent drive.